Means for producing ignition-sparks.



A. KAZENMAIER. MEANS FOR PRODUGING IGNITION SPARKS. APFLIOATION FILED JAN. 17, 1913.

1,064,91 5, Patented June 17, 1913.

MTIJESSES Ibn/@ITER AUGUST KAZENMAIER, OF STUTTGART,

PATENT oFFroE.-

GERMANY, ASSIGNOR TO THE :FIRM` OF- ROBERT BOSCH, OF STUTTGART, GERMANY.

MEANS FOR PRODUCING IGNITION-SPARKS.

Specification of Letters Patent.

Patented J une 17, 1913.

Application filed January 17, 1913. Serial No. 742,659.

To all 'whom t may concern:

Be it known that I, AUGUST KAZENMAIER, a subject of the Emperor of Germany, residing at and whose post-oiiice address is Ludwig-Pfau strasse 20, Stuttgart, Germany, have invented certain new and use Improvements in Means for Producing Igniti'on-Sparks; and I do hereby decl-are the following to be a full, clear, and exact description of the inventionfsuch as will enable others skilled in the art to which it appertains to make and use the sam-e.

The present invention relates to an irnprovement in the generation of ignition sparks at the spark plug in t-he cylinder of an internal combustion engine by means of a high tension electric ignition system, which improvement consists in reducing the duration of the ignition sparks for the purpose of limiting each interval throughout which a spark occurs to substantially the interval required for the ignition of the combustible mixture; and more particularly involves the novel idea lof fixing the electrical characteristie of the sparking circuit in such manner as to allow the initial formation 'of the spark without material interference, but thereafter to bring about its rapid suppression each time, whereby a spark of snappy character, powerful at initiation but-rapidly suppressed, period to which the apparatus is adjusted and irrespective ot the speed of the engine within practical limits. f

The sparking circuit of the usual high tension elect-ric ignition system comprises a conductor portion and an insulation portion; the conductor portion including an inducing wi ding in which the sparking volt;- ages are generated and. electrical connections (including a distributor `when there are multiple cylinders) between the inducing winding and the electrodes of the spark gap; the insulation portion being the spark gap between the electrodes of the spark plug. When no spark or arc stream' is passing across the gapA between the electrodes, the resistance at the gap is extremely high andmay be considere Ato be practically ininite, as compared with the electrical resistance of the remainder of the sparking circuit. That is to say, .the conductive resistance ofthe conductor-portion 'of the circuit and the insulation resistance othe gap are of dilerent order of magnitude. When an 'arci' is effected at each sparking stream is flowing across the gap between the electrodes, the resistance at the spark gap 1s immensely reduced, the arc stream being a conductor and having a resistance of the same order of magnitude as the conductor portion of the circuit. At such .times the total resista-nce of the ordinary sparking circuit is very small. On the other hand, the electrical inductance of the inducing winding is usually considerable, so that the ratio ot' mductance to resistance in the circuit when the arc stream iis flowing, is a large quantity, `and, as is Well known, the lag of the current behind lthe electromotive `force is 'dependent upon that' rat-io. i Hence, the ignition current has a considerabletime lag behind the sparking voltage after the spark has been initiated, causing thereby the persistence of the arc stream throughout a considerable part ot' the electrical cycle. However, the initial part of the interval of sparkin-g is usually sufficient to satisfactorily ignite the combustible' gas in lthe engine cylinder,1so that the prolongation of the interval beyond this point is unnecessary and in fact is undesirable in practical operation for several reasons. `Thesparking electrodes are consumed and burned to an unnecessary degrec as a result of this action, and furthermore the function of the inducing winding is interfered with, especially at the higher speeds of the engine. As a result of the lag lof the current relatively to the sparking tion of the rotating armature'in a magneto generator, for instance, the magnetic field is distorted and weakened to such an extent, especially at `the vhigher speeds, that' the igperio'd'ef ignition may notbe high enough to jump Iacross the spark gap, whereupon no spark would be produced. Often at lower engine'speeds also, even though the electric inductive is ci. smaller valueas a result of the lower frequency, the normal operation is sometimes -int-entered with owing to the retardation or reduction of volume of the spark generated. For instance, in a four cycle engine it may happen that although the first sparking voltage effects satisfactory ignition, the second sparking voltage does not nera-te a satisfactory spark; sparking-voltage then produces a spark, while the fourth sparking voltage is unsatisfactory for the purpose; 'and so on due to the lag of voltage, and therefore relatively to the posinition"voltageg'enerated at the succeeding whereas-the t ird ing circuit by an amount of the same order ot' magnitude as the usual resistance of such ccaiductor part, that is, by increasing the conductive resistance of the conductor portion of the circuit, thereby substantially reducing the absolute value of the ratio of inductance to resistance. Said additional conductive resistance will be negligible as compared with the insulation resistance of the arc gap when the arc stream is not lowing, so that the increase of the resistance will not have any appreciable effect upon the conditions at the initiation of the spark, and will not operate to diminish the effectiveness of the spark during that first short period which is alone of importance in effecting ignition.

The accompanying drawing illustrates diagrammatically an arrangement suitable for carrying out my idea. y

The primary winding 1 of a magneto generator is connected to a mechanical interrupter 2, which is driven from the engine to periodically interrupt the primary circuit of the magneto at the proper moment of its cycle, and thereby induce a sparking voltage in the secondary winding 3. This secondary winding is grounded on one side, as indicated, and is connected on the other side by a conductor 4: to the rotatable brush 5 of the distributer, for conducting the ignition currents by way of the distributer contacts 6 and the electrical connect-ions 7 to the proper spark plugs 8 in the engine cylinders 9. I n the spark plugs these electrodes which are not connected to the distributer are grounded in the usual way so as to complete the secondary circuit.

The resistance added for the purpose of accomplishing the objects of my invention may be distributed throughout the conductor part of the sparking circuit; that is, throughout the secondary winding 3, the connection 4, the distributer 5 6 and the connection 7 to the spark plugs, or it may be concentrated and located in any portion of the circuit. I prefer,vhowever, to add the required resistance by making the secondary winding 3 of a metal 'of high specie resistance, such as new silver (nickelin), the remaining parts of the sparking circuit being of copper, as is usual. In this Way, the rat-io oi' the resistance to the inductance in t-he secondai'y circuit is in` creased to the desired value by increasing the resistance without introducing any more inductance in the circuit. than is required in the inducing winding lWy invention is, therefore, characterized by the fact that the resistance of the secondary circuit is increased to such value that when an are stream is present in the spark gap the resistance of the circuit is high compared with the inductance thereof, whereby the arc stream is rapidly suppressed and interrupted without. adversely aiiiecting the initial period of the spark. The rapidity with which the are stream is suppressed is intended to be such that by the time the mag-- neto armature reaches the position for gen` erating the succeeding sparkingl voltage, the current in the secondary winding following after the initiation of the preceding spark has been reduced to Zero or to such a small value as not to materially interfere with the generation of the succeeding sparking voltage, whereby the succeeding sparking voltage will t-hen'be of Sufficient value to produce a satisfactory ignition spark at the spark plug at the desired period of ignition.

In order to assist those skilled in the art in carrying out my invention, I mention, by way of specific example, that it has been successfully embodied in a sparking system in which the secondary winding of new silver had a resistance of 15000 ohms, as compared with the resistance 3000 ohms which a like winding of copper would have, the number of turns of the secondary winding and the other elements of the sparking circuit being as usual, so that the sparking circuit was of the normal inductance but the added resistance was 12000 ohms.

What I claim is 1. Means for shortening the spark duration in high-tension electric ignition sys tems for internal combustion engines having a sparking circuit including a spark gap and an inducing' winding for generating voltages suliicient to establish arc streams across said gap, said means comprising an added conductive resistance in the sparking circuit sufficient to substantially reduce the absolute value of the ratio of inductance tb resistance in said circuit and thereby quickly suppress the currentflowing .in the circuit to avoid the adverse influence of said current on vthe generation of the next succeeding sparking voltage, substantially as described.

2. A high tension electric ignition system for internal combustion engines having a sparking circuit including a spark gap and an inducing winding of wire having high specific resistance for generating volt.-

`ages sufficient to establish arc streams across said gap, the resistance of said winding heing suflicient to substantially reduce the abwww@ solute value 0f the ratio of inducir-ance to r@- sistance in said circuit and thereby quickly Suppress the cu'renf. owiug in the circuit i0 zwof the adverse inuence 0i said current on the generation of the next succeeding sparking voltage, substantialy as d@ scribed.

n testimony whereof a-{x my signature., m presence of two Witnesses.

AUGUST KAZENMAIER.

Nit-nasser):

PAUL WOLFART, HERMANN SCHNEIDER. 

